IoT-Based Vehicle Speed Limiter Using ESP32

Overview

A speed limiter is a device that helps control the maximum speed of a vehicle, improving road safety and reducing accidents. By integrating IoT, the system can be monitored remotely, and speed limits can be dynamically adjusted based on location, traffic rules, or vehicle type.

This project demonstrates how to build an IoT-based speed limiter using ESP32, GPS module, and vehicle control interfaces.

Features

Real-time speed monitoring using GPS
Dynamic speed limit configuration from a cloud dashboard
Over-speed alert notifications via IoT backend
Optional ignition control or throttle limitation for extreme cases
Data logging for fleet management or driver analysis

Components

ESP32 Dev Board
GPS Module (e.g., NEO-6M / NEO-M8N)
Relay / PWM interface for vehicle control (optional)
OLED Display (optional) for local speed display
Wi-Fi / GSM Module for IoT connectivity

System Architecture

GPS module continuously measures vehicle speed.
ESP32 reads GPS data and calculates speed in km/h.
Speed comparison: ESP32 checks if the current speed exceeds the allowed limit.
Alert or control action:
- Send warning to driver via OLED or buzzer
- Notify fleet manager via cloud
- Optional throttle/ignition control in extreme cases
Cloud integration allows remote speed limit adjustment and monitoring.

Example Code (ESP32 + GPS + MQTT)

#include <TinyGPS++.h>
#include <HardwareSerial.h>
#include <WiFi.h>
#include <PubSubClient.h>

// WiFi credentials
const char* ssid = "your-SSID";
const char* password = "your-PASSWORD";

// MQTT Broker
const char* mqtt_server = "broker.hivemq.com";

HardwareSerial GPSSerial(1);
TinyGPSPlus gps;
WiFiClient espClient;
PubSubClient client(espClient);

// Max speed limit (km/h)
const int MAX_SPEED = 60;

void setup() {
  Serial.begin(115200);
  GPSSerial.begin(9600, SERIAL_8N1, 16, 17); // RX, TX pins for GPS

  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nWiFi connected");

  client.setServer(mqtt_server, 1883);
}

void loop() {
  while (GPSSerial.available() > 0) {
    gps.encode(GPSSerial.read());
  }

  if (gps.speed.kmph() > 0) {
    float currentSpeed = gps.speed.kmph();
    Serial.println("Current Speed: " + String(currentSpeed) + " km/h");

    // Check speed limit
    if (currentSpeed > MAX_SPEED) {
      Serial.println("Overspeed Alert!");

      // Send alert to MQTT broker
      if (!client.connected()) reconnectMQTT();
      client.loop();
      client.publish("vehicle/speed_alert", String(currentSpeed).c_str());
    }
  }

  delay(1000);
}

void reconnectMQTT() {
  while (!client.connected()) {
    if (client.connect("ESP32SpeedLimiter")) {
      Serial.println("Connected to MQTT broker");
    } else {
      delay(1000);
    }
  }
}